Patients with schizophrenia have lower IQ as compared to the general population. Furthermore, cognitive decline has been observed even before the onset of the first episode psychosis. Whether premorbid functioning and IQ also predict long-term remission status is not yet known.

1057 patients with schizophrenia and related disorders were included in GROUP project. Premorbid Adjustment Scale (PAS), IQ and Positive and Negative Symptom Scale (PANSS) were obtained at inclusion. After 6 years 691 patients were re-examined. On 530 patients we were able to determine remission status using the PANSS remission tool. Patients were divided into two groups; those who were in remission (Rem) and those who were not (NR). Groups were compared on PAS and IQ using independent sample t-tests groups.

Analyses revealed that patients who dropped out during the follow-up of 6 years had lower IQ, and higher PANSS scores as compared to those who were remained in the study. After 6 years 58% of patients were in remission. Remission status after 6 years was associated with IQ and premorbid adjustment in childhood and adolescence at inclusion.

Poorer premorbid adjustment and lower IQ at baseline are associated with non-remission after 6 years. This suggests that in order to improve the course and outcome of schizophrenia, one should aim to detect and intervene well before the first psychotic symptoms arise.